As to whether 'the cosmos is eternal, or not', the following passage from the Cula-Malunkyovada Sutta might be helpful:

Then, when it was evening, Ven. Malunkyaputta arose from seclusion and went to the Blessed One. On arrival, having bowed down, he sat to one side. As he was sitting there he said to the Blessed One, "Lord, just now, as I was alone in seclusion, this train of thought arose in my awareness: 'These positions that are undeclared, set aside, discarded by the Blessed One... I don't approve, I don't accept that the Blessed One has not declared them to me. I'll go ask the Blessed One about this matter. If he declares to me that "The cosmos is eternal,"... or that "After death a Tathagata neither exists nor does not exist," then I will live the holy life under him. If he does not declare to me that "The cosmos is eternal,"... or that "After death a Tathagata neither exists nor does not exist," then I will renounce the training and return to the lower life.'

"Lord, if the Blessed One knows that 'The cosmos is eternal,' then may he declare to me that 'The cosmos is eternal.' If he knows that 'The cosmos is not eternal,' then may he declare to me that 'The cosmos is not eternal.' But if he doesn't know or see whether the cosmos is eternal or not eternal, then, in one who is unknowing & unseeing, the straightforward thing is to admit, 'I don't know. I don't see.'... If he doesn't know or see whether after death a Tathagata exists... does not exist... both exists & does not exist... neither exists nor does not exist,' then, in one who is unknowing & unseeing, the straightforward thing is to admit, 'I don't know. I don't see.'"

"Malunkyaputta, did I ever say to you, 'Come, Malunkyaputta, live the holy life under me, and I will declare to you that 'The cosmos is eternal,' or 'The cosmos is not eternal,' or 'The cosmos is finite,' or 'The cosmos is infinite,' or 'The soul & the body are the same,' or 'The soul is one thing and the body another,' or 'After death a Tathagata exists,' or 'After death a Tathagata does not exist,' or 'After death a Tathagata both exists & does not exist,' or 'After death a Tathagata neither exists nor does not exist'?"

"No, lord."

"And did you ever say to me, 'Lord, I will live the holy life under the Blessed One and [in return] he will declare to me that 'The cosmos is eternal,' or 'The cosmos is not eternal,' or 'The cosmos is finite,' or 'The cosmos is infinite,' or 'The soul & the body are the same,' or 'The soul is one thing and the body another,' or 'After death a Tathagata exists,' or 'After death a Tathagata does not exist,' or 'After death a Tathagata both exists & does not exist,' or 'After death a Tathagata neither exists nor does not exist'?"

"No, lord."

"Then that being the case, foolish man, who are you to be claiming grievances/making demands of anyone?

So the question as to whether the cosmos is eternal, or whether it has a beginning or not, is one of those questions that is 'set aside'. The fact of existence is dukka, which is the case, whether the Cosmos has existed eternally, or not. That is the issue which the teaching sets out to understand, not 'whether the cosmos is eternal'.

Sometimes spirituality is a liberation, and sometimes it's an alibi ~ David Brazier

why isn't everybody awaken, if samsara exist since eternal times?Do I have failure in this thought?I know that time is just a concept, but it didn't help me until know.

The actual reason sangamaji is that people do not wish to awaken. They wish to follow delusion and thus get enmired further and further in samsara. Even Buddhists. This was the observation of Buddhadassa Bhikkhu in "The Heartwood of the Bodhi Tree". Other Buddhist teachers have made this observation as well (Khandro Rinpoche for example in the Tibetan Buddhist tradition).

"Even if you practice only for an hour a day with faith and inspiration, good qualities will steadily increase. Regular practice makes it easy to transform your mind. From seeing only relative truth, you will eventually reach a profound certainty in the meaning of absolute truth."Kyabje Dilgo Khyentse Rinpoche.

Samsāra literally means ‘continuous flow’- referring to a repeating cycle of birth, life, death and re-birth. Samsāra is known as the impure part of the dependent nature and one thing that is consistently constant in it is becoming. The becoming process is the main reason for all things or happenings that we observe right here, right now, then or later. When there is a becoming process, there is a change process. When there is a change process, there is a circumstance that shapes up some sort of abilities in the dependent nature. This ability of sorts is also known as ‘energy’ in the scientific terminology. And time is merely an indicator for event; just like length, width and height are indicators for size and volume. So time is a dimension that is created by humans, not born (a non-natural existence) for the task of measurement per se.

In fact, the ‘I’ or ‘you’ or ‘we’ or nāmarūpa (5 skandhas) is purely part of the becoming processes in the dependent nature and the key element of it is energy. Both our mind and body are energy elements that would constantly orientate, transform and evolve in accordance with the subjected conditions. The physical body is shaped up as an appearance due to the existence of matter and the matter is basically concerted, aggregated or concentrated or wrapped energy.

At the same time, the existence of energy would give rise to the mind that in turn conjures up perceptions, conceptions, labels, boundaries, names, activities, shapes, relations, descriptions, stereotyping, beginning, ending, etc. The mind is a necessary pre-requisite for the circumstances of duality or multiplicity. No duality or multiplicity would arise in the non-existence of the mind. This is because there would be no subject to ponder on the other side of the object or matter. As such, we shall be clear by now that mind is the forerunner of all states. These circumstances of duality or multiplicity are merely the end result of various aggregated activities being observed, recorded and replayed by the conscious and the sub-conscious mind under the influence of conditional phenomena.

It is difficult for one to see into the ultimate truth since the dawn of time because the mind is dependent arising. In other words, the presence in the waves of dependent phenomena has clouded the mind from discerning the reality of circumstances i.e. ignorance arises. And we could see that emptiness exists in all conditional phenomena. Without emptiness, the potential movement of the mind from non-enlightenment towards a state of enlightenment would not be possible – that is to say if the mind itself existed inherently. The emptiness of inherent existence of the mind is called the Buddha nature.

why isn't everybody awaken, if samsara exist since eternal times?Do I have failure in this thought?I know that time is just a concept, but it didn't help me until know.

With loving-kindnesssangamaji

Awakening is too close. People think awakening is far away.

The Blessed One said:

"What is the All? Simply the eye & forms, ear & sounds, nose & aromas, tongue & flavors, body & tactile sensations, intellect & ideas. This, monks, is called the All. Anyone who would say, 'Repudiating this All, I will describe another,' if questioned on what exactly might be the grounds for his statement, would be unable to explain, and furthermore, would be put to grief. Why? Because it lies beyond range." Sabba Sutta.

"Even if you practice only for an hour a day with faith and inspiration, good qualities will steadily increase. Regular practice makes it easy to transform your mind. From seeing only relative truth, you will eventually reach a profound certainty in the meaning of absolute truth."Kyabje Dilgo Khyentse Rinpoche.

Lobster, 'Why are we so attached to dukkha? I don't think we are attached to Dukkha. I think the 'everyday' mind is naturally extraverted. Only a rare, ripe seeker dives within to examine, look closely at suffering and seek liberation.